This invention relates in general to safety ski bindings and has specific reference to bindings of the kind referred to more particularly as "multidirectional ski bindings", that is; ski bindings capable of producing both a lateral release and a vertical release of the ski boot under abnormal stress conditions.
As a rule and preferably, a ski binding of this type is mounted on the ski in such a manner that it cooperates with the toe end of the boot to permit the release thereof in case of torsional and/or backward fall of the skier. It could as well be used in conjunction with the heel end of the ski boot in case of torsional stress and/or forward fall of the skier.
To this end, the ski binding contemplated by the present invention comprises a boot retaining jaw, also called an end piece, pivoted in relation to the body of the device about an axis parallel to the top surface of the ski and perpendicular to the longitudinal axis thereof, the body proper being adapted to rotate about the axis of a pivot member secured to the ski and extending at right angles thereto. In the following disclosure, these two axes will be referred to as the "horizontal axis" and the "vertical axis", respectively.
The ski binding according to the present invention is also of the type wherein the body is held against movement on the vertical pivot member by means of a pair of sliding pistons carried by the body and resiliently urged against complementary cam faces formed integrally with the pivot member proper. The essential advantages characterizing safety ski bindings of this character are their great simplicity and sturdiness, the reliability of the resilient return means even in case of relatively ample angular movement of the body, and the considerable resistance of the device to shocks and jolts.
The safety ski binding contemplated in the present invention also pertains to the type wherein an upward movement of the toe device which is due either to the presence of snow under the ski boot or to a momentary forward bending of the skier's body is not attended by an increment in the torque tending to retain the ski binding body against rotation about the pivot member. This property is highly desirable from the standpoint of safety in a ski binding.
The present state of the art may be illustrated for example by reference to the French Pat. No. 69.19153. The ski binding shown in FIG. 3 of this patent comprises a jaw pivoted about a horizontal axis on the body pivoted in turn about a vertical axis. The body is held against movement in relation to both pivot means by the provision of a pair of pistons each urged by a separate spring against a pair of flat cam or flat faces formed on the vertical pivot member proper.
The end piece is held against movement in relation to the horizontal axis by means of a ball urged by a third spring. A pivoting lever is provided for transmitting the movement from the ball to one of the springs holding the body against rotation, so that when the toe piece is lifted the spring is released and the resilient pressure exerted by the relevant piston on the pivot means decreases. On the other hand, the other piston keeps bearing with the same force against the corresponding flat face. The total torque resiliently counteracting the torsion stress is thus reduced in case of upward tilting movement of the toe or end piece.
However, this device is objectionable on account of the presence of three springs which increase both the final cost and the over-all dimensions of the binding beyond reasonable limits.